Signal receiving system



Oct. 26, 1934. J. M. KANE v SIGNAL RECEIVING SYSTEM Filed July 26. 1935 amnion JAMES M. KANE Patented Oct. 16, 1934 ear ier so 6 Claims.

(Granted under the act of March 3, 1883, as amended April 30, 1928; .370 Q. G. 757) My invention relates broadly to signal receiving systems and more particularly to a high speed relay circuit for operation in a signal receiving system.

One of the objects of my invention is toprovide a circuit arrangement for a high speed relay system for insuring accurate operation of a circuit closing device in a high frequency receiving circuit at high speed.-

Another'object of my invention is to'provide a circuit arrangement for a high speed radio telegraph receiving system wherein a high frequency oscillator at a receiving station may be keyed by incoming signals for in turn control- I ling the operation of a relay for the actuation of a recording apparatus at the receiving station,

substantially independent of the amplitude of the incoming signaling energy.

Still another object of my invention is to prolivide a circuit arrangement including a source of audible oscillations which may be keyed by incoming telegraphic signals for actuating a relay circuit adapted to control any form of recording apparatus.

A further object of my invention is to provide a relay circuit arrangement for telegraphic receiving systems in which an audible oscillator may be controlled by incoming telegraphic signals of relatively feeble amplitude for control- 1 ling at any desired amplitude the operation of recording apparatus connected with the relay circuit controlled by the audible oscillator.

A still further object of my invention is'to provide a circuit arrangement for a signal receiving side in a circuit arrangement for a high speed relay system for telegraphic reception as set forth more fully in the specification hereinafter following by reference to the accompanying drawing which diagrammatically illustrates the circuit of my invention. v

The system of my invention is directed particularly to a circuit for an audio frequency unit which is connected to the output of a power amplifier in a radio telegraph receiving system or in a carrier frequency line wire telegraph system.

I have successfully used the apparatus of my invention in radio circuits employing the Baudot code for operation of automatic printer apparatus known as the Teletype. The apparatus of my invention has been successfully operated at Radio Central, in the U. S. Navy Building, at Washington, D. (2., for controlling an automatic printer by radio impulses transmitted from the U. S. Navy high power radio station at Mare Island, California. I provide a polarized relay circuit which responds to the audio frequency impulses dciivered by th output of a power amplifier. The polarized relay circuit modulates or keys an audible oscillator from its back or normally closed contacts. The output of the audible oscillator is coupled to a second polarized relay circuit which keys or operates the apparatus that requires the Baudot codesuch as the Teletype. ihe audible oscillator connects to the second polarized relay device and also to a telephone circuit by which the operation of the audible oscillator can be periodically checked. The advantages of this cascade relay circuit are twofold. First, the operation of the relay system can be monitored by listening to the audible oscillator. Second, the circuit becomes more capable of adjustment for the following reason: The adjustments of the last relay circuit are made as desired and then fixed. This part of the circuit can be assumed to be incapable of misfiring when the oscillator delivers a proper impulse. Where relays and long control lines are used to key a radio transmitter, the inductance of the coils, and the capacity of the lines will change the shape of the transmitter emission. The characters may not be clear cut with perpendicular ends, but may slant or be chopped off, showing a lagging relay action. This unsatisfactory keying will not operate apparatus utilizing the Baudot code for the blacks and whites are thrown out of proportion and shape. Any unfaithfulness of transmitted relays can be immediately detected by listening to the audible oscillator of this circuit and it can be compensated for by the ad'- justments of the bias of the electron tubes in the circuit of my invention. A character shortened by faulty transmitter relay action can, therefore, be corrected and brought to its normal shape, simultaneously correcting the time interval or white between the blacks or transmitted characters.

Referring to the'drawing in detail, reference character 1 designates the input circuit to the primary winding 2 of an audio frequency transformer 3. The secondary winding 4 of the audio frequency transformer 3 connects to the input circuit of electron tube 5. Electron tube 5 includes a cathode 5a, control grid 55 and an anode 5c. The grid circuit is adjustably biased from battery 6 shunted by potentiometer 2 with tap connection 8. Cathode 5a is heated from any suitable source of potential, which I have designated generally at 9. The output circuit of tube 5 contains milliammeter 62 and actuating coil 10 of polarized relay 12. The output circuit of tube 5 also includes resistor 11 and the source of potential 14 returning to the cathode circuit adjacent the source 9. A second electron tube 15 is provided having its input circuit leading from cathode 15a and control grid 15?) connected across resistor 11 through the bias adjusting means constituted by battery 16, potentiometer- 17 and adjustable tap 18. The output circuit of electron tube 15 extends from anode 150 through milliammeter 19 through actuator 20 of polarized relay 12 to the positive side of the source of potential 21. The cathode 15a of electron tube 15 is heated from suitable source of potential represented at 22. Armature 23 is controlled by actuating windings 10 and 20 01 polarized relay 12 coacting with the core structure 12a. A set of contacts 24 are alternately opened and closed by operation of the relay system. An audible oscillator is shown at 25 constituted by electron tube 26 having cathode 26a, grid electrode 265 and anode 26c. The input circuit of electron tube 26 between grid electrode 261) and cathode 26a is closed through inductance 27. The inductance 27 is wound upon an iron core 28 and is inductively coupled with winding 29. Winding 29 is connected in the output circuit of electron tube 26 between anode 26c and in series with resistance element 30 to the connection 31 which leads to the positive side of the source of potential 21, the circuit being completed through lead 32 to lead 33 which is connected with cathode 26a, thereby completing the output circuit of the oscillator tube 26. The output of the oscillator 26 also is coupled through a condenser 34 and an impedance 35 with the input circuit of an electron tube 36. Electron tube 36 includes cathodes 36a, control grid 36b and anode 360. The input circuit of electron tube 36 is completed from control grid 365 through impedance 35 through the adjustable tap 37 on potentiometer 38, which connects in shunt with battery 39. This bias control circuit connects to cathode circuit 6a as shown The output of electron tube 36 connects through milliammeter 41 through actuating winding 40 of polarized relay 42 and through resistor 43 to the source of potential 14, the circuit being completed through lead 44 which returns to the cathode 360.. I employ the same source of potential 14 for the output of tube 36 as is provided for the output of tube 5. It is clear however that independent sources of plate potential may be used as desired. The input circuit for electron tube 45 extends from cathode 45a through lead 46, lead 33, lead 32, lead 47 through resistor 43, lead 48, and bias control 49 to the control grid 45b. The output circuit of tube 45 extends from anode 450 through milliammeter 51 to actuating winding 50 of polarized relay 42 through lead 52, lead 31, through source of plate potential 21, returning through lead 32 and lead 33, to lead 46 and cathode 45a. It will be observed that cathodes 45a, 26a and 15a are all heated froni source 22. Cathode 36a and 5a are heated from source 9. Plate potential for electron tube 5 and electron tube 36 is supplied from source 14. Plate potential for electron tube 15, oscillator tube 26 and electron tube 45 is supplied from source 21. This provides an extremely compact arrangement of apparatus. The polarized relay 42 has a core structure 42a which actuates movable armature 53, coacting with sets of front and back contacts 54. A center lead 55 is taken from armature 53 while independent leads 56 and 57 are taken from front and back contacts 55 to provide the marking, timing and spacing contacts for connection to the Teletype or Baudot code apparatus. The back contact of the set of contacts 24 of polarized relays 12 connects through condenser 58 to one side of the input circuit of the audible frequency oscillator. The other side of the input circuit of the audible frequency oscillator connects through lead 59 to the movable armature 23. When armature 23 connects to the back contact of the set of contacts 24 the condenser 58 is placed in shunt with inductance 27, thus changing the period of 0scillation oi the audible frequency oscillator and changing the character of operation of the audible frequency oscillator 25 and effecting an operation of the second polarized relay system 42. Oscillations cease when armature 23 is restored to normal position, or so change in period as not to effect the operation of the polarized relay system 42 in the same direction as the original keying operation, aifecting the second polarized relay system. The operation of the audible frequency oscillator 25 is observed by the operator listening at telephones 61 connected through condensers 60 at points across resistance 30. Any failure of the operation of the audible frequency oscillator is immediately detected in telephones 59 which respond to the audible frequency note generated by audible frequency oscillator 25 and permitting a check to be maintained upon the operation of the audible frequency oscillator.

The operation of the two polarized relay systerms is effected at high speed for the reason that the functioning of electron tube 15 is proportional to and coacts with the functioning of electron tube 5 while the functioning of electron tube 45 is proportional to and coacts with the functioning of electron tube 36. The reason for this will be apparent when it is noted that resistor 11 in the output circuit of tube 5 is disposed in the input circuit oftube 15 so that when the polarity imparted to the grid circuit of tube 15 from the connection to resistor 11 goes positive to a great degree, the'rise in plate current in tube 15 through actuating winding 20, enables actuating winding 20 to attract armature 23 while actuating winding 10, repels armature 23, and vice versa, thus giving positive high speed actuation to armature 23. That is to say, the operation of tube 15 is differentially related to the operation of tube 5 and is directly dependent upon the current flow through resistor 11 in the output circuit of electron tube 5. Similarly, armature 53 is controlledby the cooperative relation of actuating windings 40 and 50 due to the connection of the input circuit of tube 45 across resistor 43 which is in the output circuit of tube 36. As the degree of change in the positive potential applied to the gird 45b of tube 45 through its connection with resistor 43' increases, a change is effected in plate current through actuating winding 50. Thus as the current through actuating winding 40 decreases, the plate current through actuating winding 50 increases so that while actuating winding 40 is repelling armature 53, actuating winding 50 is attracting armature 53, thus assisting in the rapid movement thereof for insuring faithful reproduction of the impulses delivered by the audible frequency oscillator.

Adjustments may be made of the grid potentials on each of the tubes 5, 15, 36, and 45, in order to insure precision operation thereof under control of high speed impulses. In the Baudot code it is highly important that the circuits respond at high speed as the impulses in the Baudot code are close together and failure of the circuits to respond to any one of the impulses will be fatal to the satisfactory operation of the Baudot apparatus. .LJ. e fact that adequate power is available from the audible frequency oscillator which is keyed at the receiver, renders the operation of the Baudot code apparatus substantially independent of the relatively weak incoming signaling energy.

While I have described my invention in one of its preferred embodiments, I desire that it be understood that modifications may be made and that no limitations upon my invention are intended other than are imposed by the scope of the appended claims.

The invention herein described may be manufactured and used by or for the Government of the United States of Al ierica for governmental purposes without the payment of any royalty thereon or therefor.

What I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. In a signal receiving system, an audio frequency signal responsive circuit, a pair of blocked grid amplifiers differentially connected with said circuit, a polarized relay having a winding disposed in each of said differentially connected blocked grid amplifiers, a set of contacts controlled by said polarized relay, an audio frequency oscillator, connections from said contacts to said audio frequency oscillator for controlling the character of operation of said oscillator, a second blocked grid differential amplifier connected with said oscillator, and a relay controlled by said second blocked grid differential amplifier, in accordance with signal impi ses impressed upon said signal responsive circuit.

2. In a signal receiving system, a circuit res onsive to audio frequency signal impulses, a differentially connected amplifier connected with said circuit, a polarized relay operated by said amplifier, an audio frequency oscillator, connections to said oscillator controlled by said relay,

second differentially connected amplifier connected with said oscillator, a polarized relay operated by said second amplifier, and means connected with said oscillator and controlled by the operation of said first mentioned polarized relay for rendering said oscillator effective upon said second mentioned polarized relay in accordance with signal impulses impressedupon said signal receiving circuit.

3. In a signal receiving system, an audio frequency signal responsive circuit, a differentially connected audio frequency amplifier electrically connected with said signal responsive circuit, a polarized relay having windings connected in the output of said differentially connected audio frequency amplifier, a second audio frequency differentially connected amplifier, a polarized relay connected with the output of said second difierentially connected audio frequency amplifier, an audio frequency oscillator and a circuit interconnecting said first mentioned polarized relay, said audio frequency oscillator, and the circuits of said second mentioned differentially connected audio frequency amplifier, for impressing signal impulses upon said second mentioned differentially connected audio frequency amplifier from said audio frequency oscillator in ace rdance with signal impulses received by said audio frequency signal responsive circuit.

i. A telegraphic signal receiving system comprising an audio frequency signal responsive circui a differential amplifier constituted by a pair of alternately operating electron tube circuits connected with said signal responsive circuit, a polarized relay having one winding thereof individual to the output circuits of each of said electron tubes, an armature controlling a set of contacts actuated said relay windings, an audio frequency oscillator, a second differential ampllfier comprising a pair of alternately operating electron tubes, a polarized relay controlled by second differentially connected amplifier, and a circuit interconnecting the contacts of said first mentioned polarized relay with said audio .'equency oscillator and with said second differentially connected amplifier for impressing impulses from said oscillator upon said second different ally connected amplifier in accordance with quency signal impulses delivered by said signal responsive circuit.

5. A telegraphic signal receiving system comprising audio frequency signal responsive circuit, a differential amplifier connected with said circuit, a polarized relay having a pair of actuating wi din s operated by said amplifier, an audio erated audio frequency amplifier, a polarized reay actuated said second erentially operated amplifier, a keying circuit interconnecting said rst mentioned polarized reoscillator with said l lay, connections between the output of said oscillator and said second mentioned difierentially connected ampl l, and a signal observing circuit connected w h said oscillator for checking the character of impulse impressed by said oscillator upon said second mentioned differential amplifier in accordance with the signal impulses received by said signal responsive circuit.

6. In a signal receiving system, an audio frequency signal receiving circuit, a difierential amplifier connected with said signal receiving circuit, said amplifier comprising alternately operating electron tubes, a polarized relay having windings connected with the circuits of said electron an audio frequency oscillator, a second differentially connected audio frequency amplifier constituted by separate electron tubes operating successively, a second polarized relay having its windings connected in the output circuits of said second differentially connected amplifier, a common source of power for the power circuits of corresponding tubes in each of said differentially connected amplifiers, and circuits interconnecting said audio frequency oscillator, said second mentioned differentially connected amplifier and said first mentioned polarized relay for impressing signal impulses from said audio frequency oscillator upon said second mentioned differentially connected amplifier under control of signal impulses impressed upon said signal responsive circuit.

JAMES M. KANE. 

